This invention relates to an antenna system and more particularly to an antenna system suitable for point-to-multi-point communication and an associated method.
Point-to-multi-point communications in fixed and cellular networks typically involve base stations comprising single or sectorized antennas serving many clients with telecommunication services such as data, voice and multi-media. These services suffer from a number of problems, mainly capacity constraints. Capacity may be increased in various ways, such as creating multiple sectors around a base station and/or increasing the number of frequency channels available. The latter has real limitations since frequency spectrum, especially for high-speed data, which is associated with more bandwidth, is not readily available. With the former and when more sectors are created, more frequencies are also typically required, since frequency interference prevents frequencies to be reused in sectors on the base station. Alternatively, capacity may be increased by creating more cells (base stations), each with a smaller coverage area, but this is expensive due to the infrastructure required. Further, an omni-directional antenna or sector antenna often does not provide sufficient gain to users in its beam, since antenna beam-width is inversely related to antenna gain and hence signal strength. Antenna gain may be increased by reducing the angular size of the sectors, but costs, practical constraints, such as number and size of antennas, frequency planning and other technical issues make it impractical to use sectors smaller than about 120 degrees (3 sectors per base station) or 90 degrees (4 sectors per base station).